Fig. 1. Patterns of microbial metabolic efficiency and resource acquisition strategies along the altitude gradient.

a Metabolic efficiency, including metabolic quotient (qCO₂, respiration per unit biomass, μg CO₂–C μg⁻¹ MBC h⁻¹) and carbon use efficiency (CUE); b microbial resource acquisition strategy. The Vlength quantified the relative C vs. nutrient (N and P)-acquiring enzyme activities, and lower Vlength indicated relative higher nutrient acquisition strategies (relative to C); the Vangle quantified the relative P vs. N-acquiring enzyme activities, and higher Vangle represented relatively higher P vs. N acquisition strategies.